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As we discussed earlier, grade-separated intersections are provided to separate
the traffic in the vertical grade.
But the traffic need not be those pertaining to road only.
When a railway line crosses a road, then also grade separators are used.
Different types of grade-separators are flyovers and interchange.
Flyovers itself are subdivided into overpass and underpass.
When two roads cross at a point, if the road having major traffic is elevated
to a higher grade for further movement of traffic, then such structures are
called overpass.
Otherwise, if the major road is depressed to a lower level to cross another by
means of an under bridge or tunnel, it is called under-pass.
Interchange is a system where traffic between two or more roadways flows at
different levels in the grade separated junctions.
Common types of interchange include trumpet interchange, diamond interchange ,
and cloverleaf interchange.
- Trumpet interchange: Trumpet interchange is a popular form of three
leg interchange.
If one of the legs of the interchange meets a highway at some angle but does
not cross it, then the interchange is called trumpet interchange.
A typical layout of trumpet interchange is shown in figure 1.
Figure 1:
Trumpet interchange
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